4.1: Diversity of Bacteria

Question 1

which phylum includes many of the most commonly encountered bacteria?

Answer 1

Proteobacteria

Question 2

what phylum is most metabolically diverse? what metabolic lifestylese does it include?

Answer 2

Proteobacteria, includes:
* chemolithotrophs
* chemoorganotrophs
* anoxygenic phototrophs
* faculatative organisms that can switch from one metabolic lifestyle to another

Question 3

what are the 5 classes proteobacteria is divided into? which 3 are well studied, which 2 are smaller classes with a broad range of phenotypes?

Answer 3

• Alpha-, Beta-, Gamma- are well studied with many important species
• Delta, Epsilon- are smaller classes but with a broad range of phenotypes

Question 4

What’s included in the Class Alphaproteobacteria within Proteobacteria

Answer 4

• includes pathogens and non-pathogens

Question 5

what’s an example of a non-pathogen Alphaprotebacteria? what does it do?

Answer 5

Rhizobium leguminosarum
* forms root nodule on legume plants (particularly soy beans)
* symbiotic relationship with the plant: (both benefit)
-baterium fixes nitrogen from soil into bioavailable form for plant
-plant provides nutrients and a home for the bacteria living in root nodule

Question 6

what’s an example of a pathogen Alphaproteobacteria? what is it and what does it cause? what’s special about this pathogen?

Answer 6

• Rickettsia rickettsii
• obligate intracellular pathogen
• carried by insects and transmitted by insect bites
• causes “Rocky Mountain spotted fever” (in humans)
• Phylogenetically, Rickettsia is the closest relative to the eukaryotic mitochondrion.

Question 7

whats included in the class Betaproteobacteria?

Answer 7

• Metabolically diverse, some are pathogens, some are non-pathogens

Question 8

what’s an example of a nonpathogenic Betaproteobacteria? where does it live and what does it do?

Answer 8

• Neisseria mucosa
• lives on mucous membranes
• commensal of the human body = doesn’t do anything good or bad

Question 9

what’s an example of a pathogenic Betaproteobacteria? where does it live and what does it cause?

Answer 9

• Neissaria gonorrhoeae
• lives on mucous membranes
• causes the STI gonorrhea

Question 10

what characterizes the Class Gammaproteobacteria (within proteobacteria)

Answer 10

• metabolically and ecologically diverse
• many grow well in the lab and have become important research models

Question 11

what are the two examples of Gammaproteobacteria?

Answer 11

• E. coli
• Pseudomonas aeruginosa

Question 12

what are the 6 diagnostic characteristics of E. coli within Gammaproteobacteria? and what does it serve as

Answer 12

• Gram negative
• rod shaped
• facultative anaerobe
• motile by means of peritrichous flagella
• ferments lactose to mixture of acids and alcohols
• resident of large intestine of warm-blooded animals
  -serves as important indictator of fecal contamination

Question 13

what are the diagnostic characteristics of Pseudomonas aeruginosa within Gammaproteobacteria? what does it cause?

Answer 13

• gram negative
• rod shaped
• motile by means of polar flagella (comes from one end)
• naturally resistant to many antibiotics and disinfectants
• opportunistic pathogen -causes infections in immunocompromised patients (but would not make a normal healthy adult sick)
• ex. Respirator tract infections in cystic fibrosis patients

Question 14

what does the class Deltaproteobacteria contain? what are 2 examples? and what do these examples have in common?

Answer 14

• contains many species with strange behaviour, such as myxobacteria
• examples: Myxococcus xanthus, and Bdellovibrio bacteriovorus
• both predators in different ways

Question 15

describe the characteristics of Myxococcus xanthus of Deltaproteobacteria

Answer 15

• Gliding motility
• predatory -releases exoenzymes to lyse other bacteria for nutrients
• When starved -cells migrate together to form complex multicellular fruiting bodies
  -individual cells differentiate into myxospores for dispersal (somewhat resistant but not as much as endospores)

Question 16

describe the characteristics of Bdellovirbrio bacteriovorus of Deltaproteobacteria

Answer 16

• Curved, highly motile predator of other Proteobacteria and other Gram negative bacteria
• Penetrates the cell wall of prey and multiples in the periplasm (by elongating then splitting into many cells not binary fission)
• It’s parasitic -so it uses macromolecules obtained directly from the host

Question 17

Class: Epsilonproteobacteria describe it

Answer 17

• a small class, mostly famous for a few microaerophilic, spirillum shaped pathogens

Question 18

what does Campylobacter jejuni do?

Answer 18

• Frequently transmitted in under-cooked chicken
• one of the most common causes of food-borne illness

Question 19

describe phylum cyanobacteria morphology

Answer 19

• impressive morphological diversity, generally larger than other bacteria
  -unicellular, filamentous, or branching filamentous
  -some form heterocysts -specialized nitrogen fixing cells

Question 20

describe cyanobacteria cell walls

Answer 20

• unlike chloroplasts they have cell walls
• contain peptidoglycan
• gram negative cell wall type

Question 21

prokaryotes that carry out oxygenic photosynthesis belong to what phylum

Answer 21

cyanobacteria

Question 22

are cyanobacteria autotrophs or heterotrophs?

Answer 22

• autotrophs -they fix CO2 to build cell material (Calvin cycle)

Question 23

how are cyanobacteria like and unlike chloroplasts

Answer 23

• like chloroplasts they carry out photosynthesis in specialized membranes called thylakoids
• unlike chloroplasts they have cell walls

Question 24

where do cyanobacteria live

Answer 24

• widely distributed in terrestial, freshwater and marine habitats

Question 25

describe cyanobacteria nutritional requirements

Answer 25

* lowest nutritional requirements of any organism * primary producer

Question 26

describe an example of cyanobacteria

Answer 26

* *Prochlorococcus* * One of the most abundant organisms on Earth * Accounts for ~half of photosynthesis in the World's oceans. * up to 35% of oxygen comes from this genus

Question 27

what is the only cyanobacteria discovered that is not photsynthetic? describe why it was misidentified, and what it does

Answer 27

*Vampirovibrio chorellavorus* * discovered in 1972, but misidentified as a member of the *Deltaproteobacteria*, because it's an obligate pathogen of the eukaryotic algae Chlorella, it was thought to be a predator, behaving the same as deltaproteobacteria * what it does: -attaches to the surface of algal cells using Type IV pili -injects the alga with digestive enzymes and eats the nutrients -phylogenetically, it belongs to a group of heterotrophs that cluster within Cyanobacteria

Question 28

describe phylum firmicutes what does it include?

Answer 28

* one of two phyla with gram positive cell walls (phyla with most gram positives) * low GC Gram positives (have low proportion of GC nucleotide pairs in DNA) * Includes lactic acid bacteria - aerotolerant anaerobes that produce lactic acid as an endproducts of fermentation * also many non-lactic acid bacteria * all endospore formers belong to this group

Question 29

describe 2 examples of bacteria that do lactic acid fermentation within phylum Firmicutes, which one's good which one is bad

Answer 29

* Lactobacillus delbrueckii -yogurt production (considered good) * Streptococcus pyogenes -cause of strep throat, scarlet fever, and flesh eating disease (bad)

Question 30

describe an example of non-lactic acid bacteria within firmicutes

Answer 30

*Staphylococcus aureus* * facultative anaerobe that forms characterisitc grape-like clusters * lives on skin * Halotolerant - can be isolated using media with high NaCl, like mannitol salt agar * frequent cause of nosocomial infections (an infection that someone specifically gets in a hospital, since s. aureus lives on skin of health care workers)

Question 31

what are the two best studied genera of endospore formers?

Answer 31

* Bacillus -aerobic endospore formers * Clostridium -strictly anaerobic endospore formers

Question 32

where are endospore forming firmicutes primarily found, are they pathogenic, nonpathogenic or both?

Answer 32

* Endospore formers are found primarily in soil * Most are non-pathogenic **saprophytic** (degrader) soil organisms * some however can be dangerous pathogens!

Question 33

describe the example of endospore forming firmicutes within the genera Bacillus, what is it used for

Answer 33

Bacillus subtilis * important lab bacterium used as a model for: * Gram positive cell structure and genetics * Cell division and differentiation (into endospores)

Question 34

describe the example of endospore forming firmicutes within the genera Clostridium, what is it, what does it do

Answer 34

Clostridium botulinum * Strict anaerobe with a fermentative metabolism * lives in tiny anoxic pockets in the soil * secretes a variety of exoenzymes to degrade plant material * can also grow in anaerobic canned foods * produces a deadly neurotoxin, which when consumed causes botulism

Question 35

what are the proper canning procedures needed to prevent Clostridium botulinum from growing in the anaerobic environment of canned foods (so it don't produce neurotoxin)

Answer 35

* reach temp above 120 C to destroy endospores * or include enough acid or sugar to prevent germination

Question 36

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